Eye-tracking during reading

What can we learn from the measures?

Daniela Palleschi

Humboldt-Universität zu Berlin

2023-04-12

Eye-tracking

  • in (psycho)linguistics
    • during reading
    • visual world paradigm
  • in psychology
    • pupillometry
    • visual search
  • but also
    • market research
    • diagnostic tool

Eye movements

  • saccades: eye movements (e.g., from one word to another)
    • average saccade legnth: 7-9 letters (in alphabetic writing systems)
  • fixations: ‘looking at’ something, e.g., a word (little movement)
    • when information is taken in
    • average duration: 225-250ms (ranging 50-600ms)
  • regressions: saccades to earlier text
    • occurance: 10-15% of saccades in skilled readers

Rayner (2009)

The eye-tracker

  • eye-tracker
    • camera \(+\) infrared illuminator
  • screen
  • chin/head rest
  • in our lab: desk-mounted

Image source: SR Research (all rights reserved)

Eye-tracking during reading

Eye-tracking reading measures

  • inform theories of language processing via linking hypotheses
    • linking visual attention to processing
  • typically, we compare reading times as a function of some manipulation
    • e.g., Sally went/goed to the store.
  • longer reading times are taken to reflect processing costs, associated with e.g., sentence complexity or anomalies

Region of interest (ROI)

  • can be anything on-screen
    • sentence-level
    • word/region-level
    • a certain part of the screen

Measures (dependent variables)

  • what we measure = dependent variables (usually…)
    • their value depends on some predictor (e.g., word frequency)
  • measures of duration (time spent on a region)
    • first fixation
    • first-pass reading time
    • regression path duration
    • total reading time
  • data type: continuous
  • measures of revisits
    • number of fixations
    • number of regressions in/out
    • regression in/out (yes or no)
    • probability of regressions in/out (0:1)
  • data type: binary (0,1) or count

Independent variables

  • Word properties
    • word frequency
    • word length
  • Sentence-level influences
    • context (i.e., prediction)
    • semantic or grammatical manipulations
  • Inter- and intra-individual
    • domain-specific expertise
    • reading skill level

What do these measures tell us?

  • eye-tracking during reading can tell use when and where processing costs are incurred
  • early measures involve “first contact with a word” or region: first-fixation, first-pass reading time (Vasishth et al., 2013, p. 126)
  • late measures involve regressions to a region: e.g., total reading time
    • may also include ‘spillover’ effects from early processing
  • eye-tracking during reading measures can therefore tell us about stages of processing

References

Clifton, C., & Staub, A. (2011). Syntactic influences on eye movements during reading. In Oxford Handbook of Eye Movements. Oxford University Press. https://doi.org/10.1093/oxfordhb/9780199539789.013.0049
Juhasz, B. J., & Pollatsek, A. (2011). Lexical influences on eye movements in reading. In Oxford Handbook of Eye Movements.
Rayner, K. (2009). Eye movements and attention in reading, scene perception, and visual search (Vol. 62, Issue 8). https://doi.org/10.1080/17470210902816461
Rayner, K., & Liversedge, S. P. (2011). Linguistic and cognitive influences on eye-movements during reading. In Oxford Handbook of Eye Movements.
Vasishth, S., von der Malsburg, T., & Engelmann, F. (2013). What eye movements can tell us about sentence comprehension. Wiley Interdisciplinary Reviews: Cognitive Science, 4(2), 125–134. https://doi.org/10.1002/wcs.1209
Warren, T. (2011). The influence of implausibility and anomaly on eye movements during reading. In Oxford Handbook of Eye Movements.